Drilling machine for use with selftapping service t



June 4, 1957 F. H. MUELLER 2,794,352

DRILLING MACHINE FOR USE WITH SELF-TAPPING-SERVICE T 7 Filed Feb. .15, 1955 INVENTOR FRANK H. MUELLER all/ W ATTORNEY United States Patent DRILLING MACHINE FOR USE WITH SELF- TAPPING SERVICE T Frank H. Mueller, Decatur, 111., assignor to (10., Decatur, 111., a corporation of Illinois Application February 15, 1955, Serial No. 488,184

2 Claims. (CI. 7742) This invention relates to improvements in drilling machines used in conjunction with self-tapping service Ts and more particularly to a drilling machine of simplified design to be used with a self-tapping plastic T of the type described in my co-pending application Serial Number 410,587, filed February 16, 1954, and entitled Service T for Plastic Mains.

The T disclosed in the aforementioned application is constructed of plastic material and has a longitudinallyextending through bore and a lateral outlet with the lower and inlet end of the T being shaped as a saddle for engagement with and solvent-welding to a plastic main. The T through bore is interiorly threaded for a portion of its length and contains an eXteriorly-threaded longitudinally-adjustable cutting plug, which has a non-circular socket in its upper end and a circular cutting blade secured to its lower end. Positioned adjacent the upper end of the T through bore is an annular sealing means, such as an O-Iing, which eifectively prevents the escape of any fluid from upper end of the T when the plug is positioned in its uppermost position, in sealing engagement with the O-ring. Also utilized with the T is a plug-turning tool which has a smooth cylindrical shank portion sealingly engageable with the O-ring, and a lower end complementary to the plug socket.

In use of the T to connect a plastic service line to a plastic main, the T is solvent-welded onto the main and, after the service line is solvent-welded to the T lateral outlets, the cutting plug is screwed downwardly by use of the plug-turning tool until the cutting lade cuts a hole through the wall of the main. The plug is then screwed rearwardly until it abuts and sealingly engages the O-ring. Since the cylindrical shank portion of the plug-turning tool is of a slightly greater diameter than the inner diameter of the O-ring, the coaction of the two effectively prethat when a tap is made into a main the resulting pressure in the T through bore acts to force the plug-turning tool out of the bore. It will be easily appreciated that with a high pressure acting on the entire cross sectional area of the tool, there will be a large force urging the tool out of the plug socket and out of the bore. Consequently, when tapping a high pressure main, it has been found that an operator is required to exert a great deal of axial force on the tool in order to maintain it in operative position. Of course, in the event that the operators hand should slip or that he should lose control of the tool for any reason whatsoever, the tool could be forced from the plug socket and T bore with great force and injure the operator or any other person who might be standing nearby, as well as permitting fluid to escape from the T.

Accordingly, it is a principal object of this invention to provide a drilling machine for use with a self-tapping T of the type described which eliminates any possibility of fluidpressure blowing the plug-rotating tool out of the T during the tapping operation.

Another object of this invention is to provide a simply constructed and economical drilling machine for use with plastic tapping Ts to accomplish the above object.

A further object of this invention is the provision of a drilling machine for use with a plastic tapping T which co-acts with said T to prevent the escape of fluids during the tapping operation.

Other objects and advantages of this invention will be in part apparent and in part explained by the following description and accompanying drawings, in which:

Figure 1 is a side elevational view, in part full and in part sectional, showing a drilling machine embodying this invention connected to a self-tapping service T that is solvent welded to a main. The component parts are shown in their positions immediately after the main has been tapped;

Figure 2 is a sectional view taken on line 2-2 of Figure 1; and

Figure 3 is a side elevational view of the T shown in Figure 1 after the tapping operation has been completed and the drilling machine disconnected. Part of the wall of the T is broken away to show the final position of the plug.

Referring specifically to the drawings, the tapping T 10 is provided with a lateral outlet 12 and a through bore 14 having interior threads 16 for a portion of its length. Threadably engaged within the bore 14 is an exteriorly threaded rotatable cutting plug 18 having a non-circular socket 20 formed in its upper end and a circular cutting blade 22 secured to its lower end. It will further be noted that the upper end of the plug 18 has a short cylindrical section 24 of reduced diameter for reasons later described.

Adjacent the upper end of the through bore 14 is an interior circumferential groove 26 containing a sealing O-ring 28. Referring now to Figure 3, it will be noted that when the plug 18 is in its uppermost position, the section 24 engages within and seals with the G-ring 28, thereby preventing the escape of any fluid past this point. It will further be noted that a closure cap 30, adapted to be screwed onto exterior threads 32 of the T after the tapping operation, has a centrally depending cylindrical boss 34 also sealingly engageable with the inner peripheral surface of the O-ring 28.

Referring once again to Figure 1, a drilling machine 36 embodying this invention comprises a generally cylindrically shaped hollow body member 38 provided with sidewall cut-outs 40, and a plug-rotating tool 42. The body member 38 is provided, at its lower end, with an opening 44 having a counterbore provided with threads 46 adapted to engage with the T threads 32 to mount the drilling machine on the T. The upper end of the body member 38 has a somewhat smaller opening provided with interior threads 48 of the same pitch as the threads 16 of the through bore 14, for reasons explained more fully later.

The plug-rotating tool 42 comprises a cylindrical shank portion 50 terminating at its lower end in a plug engaging head 52 complementary to the plug socket 20. The diameter of the shank portion 50 is slightly greater than the inner diameter of the O-ring 28 for sealing engagement therewith. Above the shank portion 50 the tool 42 is provided with exterior threads 54 engageable with the threads 48 in the body member 38. At its upper end the plug-turning tool 42 has a non-circular projection 56 engageable by a brace (not shown), or similar tool, for rotating the tool 42.

Thus when a tap is to be made, after the T 10 has been secured to main 58 and a service line 60 connected up, the drilling machine 36 is positioned over the T and the head 3 52,0f the tool 42 is inserted into the plug socketZO. The body member 38, which is threadably engaged with the threads 54 on the tool 42 is then screwed down onto the exterior threads 32, of-the T to 'mount-the drilling machine thereon. With body member 38 thus secured, the tool 42 is then rotated to screw the tapping plug 18 downwardly and tap the main 58 as described in the aforementioned application. Inthis connection, it will be seen that because the threads 16 and 48 are of the same pitch, the tool 42 can advance the plug 18 downwardly without binding of either or disengaging the tool head 52 from the plug socket 29.

Since the cylindricalshank portion 50 has a diameter slightly greater than the inner diameter of the O-ring 28,

the shank 51 will sealingly engage within the Owing '28 to thereby prevent the escape of fluid after the main 58 has been tapped. On this latter event, since the upper end of the through bore 14 is so sealed, the fluid, which works its way upwardly between the plug and bore threads, will have no means of escape therefrom. The consequent inability of this fluid to escape will cause it to work into socket 20 and exert a strong upward force against the entire cross sectional area of plug shank 50. It is easily seen then that in the past when there was no means provided for the retention of tool 42, the fluid pressure could forcibly blow it out of the socket 20 and completely out of the bore 14. However, in the present instance, since the tool 42 is threadably connected to, the body member 38 and since the latter is secured ,to the T 10 there is no possibility of the tool being forced from its operating position. v

The final step required to complete the tapping operation is to move plug 18 by the tool 42 once again to its uppermost position so that the section 24 sealingly engages the O-ring 28, remove thedrilling machine 36 from the T 10 and replace the cap 30. p

It will thus be seen that the objects of this invention have been fully and eflectively accomplished. It will be realized, however, that various changes will be made in the specific embodiment shown and described to illus-' trate the principles of the invention without departure from such principles. Therefore, this invention includes all modifications incorporated within the spirit andtscope of the following claims.

I claim: 7 t

l. A plug turning machine for use with a self-tapping service T having a through bore and a lateral outlet, one end thereof shaped for engagement with andsolvent-Welding to a plastic main, an interior thread in the bore, ,a

4 tapping plug disposed entirely within the bore and threadably engaged with the bore thread, and annular sealing means mounted in the bore adjacent the other end of the T and engageable by the plug, the inner diameter of the sealing means being less than that of the crest diameter of the bore thread, said, machine comprising: a tubular body member, detachably securable to the T other end and having interior threads coaxial with and of the same pitch as the bore threads; and an elongated plug turning tool threadably engaged with said body member threads for extending into the T bore and detachably engaging the plug for rotating the latter, said tool having a smooth cylindrical shank portion of slightly greater diameter than the inner diameter of the annular sealing means and sealingly engageable with the inner periphery thereof.

2. A plug turning machine for use with a self-tapping service T having ,a' through bore and a lateral outlet, one

end thereof shaped for engagement with and solvent-weld-t ing to a plastic main, an interior thread in the bore, .a tapping plug disposed entirely within the bore and threadably engaged with the bore thread, and an O-ring seal mounted inthe bore adjacent the other end of the T and engageable by the plug, the inner diameter of the O-ring being less than that of the crest diameter of the bore thread, a non-circular socket in that end of the plug facing the O-ring, and an exterior thread on theother end i of the T, said machine comprising: a tubular body memtool.

References Cited in the file of this patent UNITED STATES PATENTS 1,631,564 Van Raalte June 7, '1927' 1,664,796 Spangle Apr. 3, 1928 2,498,831 Veitc-h Feb. 28, 1950 2,515,260 Pichler July 8, 195,0 

